More than 30 million American adults have diabetes, the seventh leading cause of death in the United States, according to the Atlanta-based Centers for Disease Control and Prevention. And while research has long shown that weight loss can help either prevent or delay the onset of the chronic disease, little is known about alcohol's effects.

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Researchers at the University of Pennsylvania School of Nursing sought to address the role of alcohol intake and whether it influences weight loss in individuals with Type 2 diabetes.

They followed 4,901 overweight people with diabetes for four years and divided them into two groups: a control group with diabetes support and education and an Intensive Lifestyle Intervention (ILI) group.

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After four years, data showed participants in the ILI group who abstained from alcohol lost more weight than those who drank any amount of alcohol during the intervention.

Heavy drinkers were also less likely to have clinically significant weight loss over the four-year period.

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"This study indicates that while alcohol consumption is not associated with short-term weight loss during a lifestyle intervention, it is associated with worse long-term weight loss in participants with overweight or obesity and Type 2 diabetes," lead researcher Ariana M. Chao said in a university statement. "Patients with Type 2 diabetes who are trying to lose weight should be encouraged to limit alcohol consumption."

Alcoholic beverages are known to be a significant contributor of calories in American diets, according to the study. More than 70 percent of Americans say they consume alcohol at least once a year.

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Unlike proteins, carbohydrates or fats, alcohol isn't stored in the body, but used for fuel, "thus decreasing the body's use of other sources of calories," the New York Times reported last year. "That means people who drink must eat less or exercise more to maintain their weight."

The new research was recently published in the journal Obesity.